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Research May Lead to More Effective Avian Influenza Vaccine


November 24, 2009
By University of Guelph

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November 24, 2009, Guelph, Ont. – University of Guelph scientists have made a discovery that may lead to more effective vaccines to protect poultry and humans from the deadly avian influenza virus.

November 24, 2009, Guelph, Ont. –
University of Guelph scientists have made a discovery that may lead to
more effective vaccines to protect poultry and humans from the deadly
avian influenza virus.

"We have found one of the molecular determinants of the H5N1 avian influenza
virus that can induce immune responses in chickens," said Prof. Shayan
Sharif, a researcher in the Department of Pathobiology and lead author of
the study published recently in the journal PLoS ONE.

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"This molecular structure may be used in the future for protecting chickens
against avian flu and possibly for control of transmission of the virus from
birds to humans."

Public concern about this year's H1N1 flu pandemic has overshadowed the
potential threat of its close cousin – H5N1 avian influenza virus. But
scientists and public health officials have been keeping a close watch on a
deadly strain of H5N1 virus that has been circulating for more than a decade
in Eurasia. The World Health Organization reports that since 2003, there
have been 442 confirmed cases of people being infected with H5N1 virus; of
those, 262 have died.

While the numbers seem small in comparison to the thousands of people
infected by H1N1 worldwide, H5N1 is far more lethal: while most H1N1
infections result in only mild illness, about 60 per cent of people infected
by the H5 virus have died. Luckily, so far the virus cannot be easily
transmitted from person to person, Sharif said. But that could change.

"Influenza viruses are constantly changing and it is possible that the H5
virus could develop into something that is more efficiently transmitted from
birds to humans and, more importantly, from person to person," he said. "If
that happens, then we may face a pandemic of massive proportions."

The H5 avian influenza virus is commonly found in wild birds such as
migratory waterfowl that are usually unaffected by the virus. They can,
however, transmit the virus to a variety of domestic birds including
chickens, in which it can cause a range of illness from no signs of disease
at all to a severe epidemic that kills all infected birds.
Vaccines are available to protect domestic poultry from H5N1 virus. However,
very little is known about how the chicken's immune system interacts with
the virus.

The molecular region identified by Sharif's research team is a small peptide
contained in the hemagglutinin (HA) antigen, a protein found on the surface
of the flu virus. The researchers showed that the peptide is recognized by
the chicken's T-cells, which attack the virus directly and also trigger the
production of antibodies that help the immune system fight the infection.
This is the first time scientists have identified a T-cell epitope of an
influenza virus- a protein on a virus particle recognized by the immune
system – in chickens.

"This is an important step toward developing more efficacious vaccines
against H5 avian influenza in chickens," said Sharif. "We may be able to use
this epitope in future vaccines to not only protect domestic flocks but also
to prevent or control the spread of the virus from birds to humans. However,
this still needs to be confirmed experimentally and that will be the focus
of our future research."